Heretofore, in an automated assembly line for automobiles, an assembly process has been carried out in which clamping is performed by a clamp apparatus under a condition in which preformed body panels are positioned in an overlaid manner and the body panels are welded together.
The present applicant has proposed an electric clamp apparatus as disclosed in Japanese Laid-Open Patent Publication No. 2001-105332. The electric clamp apparatus is equipped with a body, a rotary drive unit disposed in the interior of the body, and a clamp arm, which projects outwardly with respect to the body. By transmitting a rotary drive force of the rotary drive unit to a ball screw mechanism, the clamp arm is operated through a toggle link mechanism so as to rotate through a predetermined angle for clamping a workpiece or the like, for example.